Mine was the same way. You can try taking yours out and carrying her into the yard away from the coop. Mine would go out, use the "potty" have a quick dust bath, eat a little, and be back on the nest in 20 - 30 minutes. In the whole time she was broody, mine only left the nest once on her own. I took her out once each day to check the next and allow her to get out. Once she got to day 14 or so I put food and water in her nest box and she ate well. Her eggs hatched just fine.
Can you find some eggs locally? Check on Craiglist or the BYC form for your state. I had really good luck buying local eggs and hatching them. You'll have a better hatch rate and won't have to pay for shipping.
I did a web search and was amazed at the farmers within 30 miles that were selling hatching eggs and different varieties of chickens.
Have to slam on the brakes so I don't over do it!
I did have one that got all the way out of the shell but did not absorb all the yolk and did not make it past it's first day but that was before I was moving her to check on the chicks.
I moved my hen all around with out problems. She even quit sitting on a late hatcher and I kept putting her back. Poor egg was pipping the whole day and rolling everytime I sat her back on it. I never thought it would hatch. I woke up the next morning to a beautiful chick.
I think it wasn't strong enough to make it out all the way.
